Combustion control system



Oct. 22, 1957 4 COARJE SPRAY D. R. TROWBRIDGE 2,810,261

COMBUSTION CONTROL SYSTEM Filed Oct. 6, 1953 cones: awm Y m1; SPRAY United States Patent COMBUSTION CONTROL SYSTEM David Roy Trowbridge, Hornchurch, England, assignor to The Plessey Company Limited, Ilford, England, a British company Application October 6, 1953, Serial No. 384,472

Claims priority, application Great Britain October 15, 1952 3 Claims. (Cl. 60-39.82)

This invention relates to a new or improved combustion chamber for starter type turbines.

With combustion systems burning liquid mono-fuels, and using air or similar gaseous oxidants together with an electric spark method for ignition purposes, it has been found that ignition is sensitive to combustion chamber temperature. As a result of this, if atomizers are used which give a fixed degree of atomisation to the fuel being injected into the combustion chamber then, for a given oxidant supply the resultant mixture will be ignitable over a limited temperature range.

An object of this invention is to provide a system which will give satisfactory ignition over a wide temperature range.

According to this invention the combustion chambers for starter type turbines is provided with means for producing two or more zones of ignition by injecting liquid fuel into the respective zones in such a manner that a finer spray can be admitted to at least one zone, whereby each zone allows satisfactory ignition over a subdivision of the total temperature range.

The ignitable temperature range of each subdivision preferably overlaps the range of one or more of the other zones, so that at any temperature within the chosen range, at least one of the zones will enable ignition to be achieved. The resultant flame front will then propagate to the remaining zones, and, because of the high temperature of the flame, ignite the mixture in each zone which would not normally be ignited by the electric spark.

The invention will now be described with reference to the accompanying drawing in which:

Fig. 1 is a sectional elevation of a combustion chamber,

Fig. 2 is a section on line AB of Fig. 1,

Fig. 3 is a sectional elevation of a modified form of combustion,

Fig. 4 is a section on line CD of Fig. 3.

Fig. 5 is a sectional elevation of two inter-communicating combustion chambers and Fig. 6 is a section on line E-F on Fig. 5.

Referring to Figs. 1 and 2. A combustion chamber 1 has an atomizer 2 fitted in the head of the chamber I. Said atomizer is fitted with two pairs of spray nozzles 3, 4, one pair 3 giving a finer fuel spray than the other pair 4, and each pair 3, 4 is so arranged that when the fuel, together with the oxidant is injected into the combustion chamber 1, two zones of differing mixture strength are provided.

Two electric spark plugs 5 are located in the chamber 1 at diametrical opposite positions and in relation to the spray from the two pairs of nozzles 3, 4 that some of the fuel spray therefrom provides an ignitable fuel in the vicinity of the ignition spark. The exhaust from the chamber 1 is by way of outlet ports 6 as shown in Fig. 1.

The advantage of this construction is that the coarser spray provides a weaker mixture which ignites at the upper limit of the temperature range, and the zone having'the finer spray gives a richer mixture which will ignite at the lower limit of the temperature range.

Referring to Figs. 3 and 4. The combustion chamber 7 is provided with a perforated partition 8 whereby the chamber 7 is separated into two inter-communicating compartments 9 and 10. The atomizer 19 has two pairs of spray nozzles 11, 12 being so arranged that the pair of nozzles 11 giving a finer spray are placed in the head of compartment 9 and the other pair of nozzles 12 are situated in the other compartment 10. A spark plug 13 is fitted in each compartment 9, 10.

The operation of this modification is similar to that above described with reference to Figs. 1 and 2. The advantage of the perforated partition 8 enables the flame from the ignited compartment to propagate to the other compartment.

A further modification is shown in Figs. 5 and 6 wherein two combustion chambers 14, 15 communicate with each other through a port 20. Each chamber 14, 15 is fitted with an atomizer 16, 17 and a sparking plug 18. Said atomizers 16, 17 provide a coarse and fine spray in the respective chambers 14, 15 and the exhaust from each chamber 14, 15 is via outlets 21. The operation of the two combustion chambers 14, 15 is as substantially the same as herein described with reference to Figs. 1 and 2.

I claim:

1. A combustion control system for insuring ignition over a wide temperature range comprising in combination a combustion chamber, a fuel atomizer having a chamber provided with at least two pairs of spray nozzles in constant communication therewith, said nozzles discharging into the combustion chamber, at least one pair of nozzles of said atomizer directing at all times a fine spray of fuel to one zone of said combustion chamber and at least another pair of nozzles of the atomizer simultaneously directing at all times a coarse spray of fuel to another zone in said chamber whereby separate jets of atomized liquid fuel in different degrees of atomization are simultaneously injected into two separate zones in said chamber, and sparking ignition means fitted into the respective zones of said chamber and simultaneously energized to ignite at least one of the atomized jets.

2. A combustion control system as set forth in claim 1 which comprises in addition, a perforated partition fitted in the chamber between the respective pairs of nozzles and extending a substantial distance throughout the length of said chamber and separating the two zones.

3. A combustion control system according to claim 1 in which the combustion chamber is divided into two portions with an intercommunicating port arranged between the respective portions.

References Cited in the file of this patent UNITED STATES PATENTS 2,407,973 Beckstrom Sept. 24, 1946 2,574,495 Parker Nov. 13, 1951 2,616,258 Mock Nov. 4, 1952 2,674,846 Bloomer et a1 Apr. 13, 1954 FOREIGN PATENTS 158,235 Great Britain May 10, 1922 616,481 Great Britain Jan. 21, 1949 38,126 France Jan. 7, 1931 

